A method and apparatus estimate an offset between a carrier frequency of a transmitter and a local reference frequency of a receiver. A received signal is separated into frequency synchronization signals and data, and a determination is made whether the frequency synchronization signals are adequate for estimating the frequency offset. This determination may be made based on, e.g., an estimated Doppler spread, an estimated signal to noise ratio, and/or an available amount of frequency offset estimation time. The frequency offset is estimated based on the determination results. If the frequency synchronization signals are adequate for estimating the frequency offset, the frequency synchronization signals are used for determining the frequency offset. Otherwise, the rate of the frequency synchronization signals is increased, e.g., by using the data as frequency synchronization signals, in which case the data is combined with the frequency synchronization signals to determine the frequency offset.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for estimating a frequency offset between a carrier frequency of a transmitter and a local reference frequency of a receiver, the method comprising the steps of: separating a received signal into frequency synchronization signals and data; determining whether the frequency synchronization signals are adequate for estimating the frequency offset; and estimating the frequency offset based on the determination result.
2. The method of claim 1 , wherein if the frequency synchronization signals are determined to be adequate for estimating the frequency offset, the frequency synchronization signals are used for estimating the frequency offset.
3. The method of claim 1 , wherein if the frequency synchronization signals are determined not to be adequate for estimating the frequency offset, the rate of the frequency synchronization signals is increased.
4. The method of claim 3 , wherein the rate is increased by using the data as frequency synchronization signals.
5. The method of claim 4 , further comprising combining the data with the frequency synchronization signals to estimate the frequency offset.
6. The method of claim 1 , wherein the step of determining is based on an estimated Doppler spread.
7. The method of claim 1 , wherein the step of determining is based on an estimated signal to noise ratio.
8. The method of claim 1 , wherein the step of determining is based on an available amount of frequency offset estimation time.
9. The method of claim 1 , wherein the frequency synchronization signals are pilot symbols.
10. The method of claim 1 , wherein the transmitter is a base station, and the receiver is a remote station.
11. An apparatus for estimating a frequency offset between a carrier frequency of a transmitter and a local reference frequency of a receiver, the apparatus comprising: a separator for separating a received signal into frequency synchronization signals and data; a controller for determining whether frequency synchronization signals are adequate for estimating the frequency offset; and a frequency offset estimator for estimating the frequency offset based on the determination by the controller.
12. The apparatus of claim 11 , wherein if the frequency synchronization signals are determined to be adequate for estimating the frequency offset, the frequency synchronization signals are used for determining the frequency offset.
13. The apparatus of claim 11 , wherein if the frequency synchronization signals are determined not to be adequate for estimating the frequency offset, the rate of the frequency synchronization signals is increased.
14. The apparatus of claim 13 , wherein the rate is increased by using the data as frequency synchronization signals.
15. The apparatus of claim 14 , further comprising a combiner for combining the data with the frequency synchronization signals to estimate the frequency offset.
16. The apparatus of claim 11 , wherein the controller determines whether the frequency synchronization signals are adequate based on an estimated Doppler spread.
17. The apparatus of claim 11 , wherein the controller determines whether the frequency synchronization signals are adequate based on an estimated signal to noise ratio.
18. The apparatus of claim 11 , wherein the controller determines whether the frequency synchronization signals are adequate based on an available amount of frequency offset estimation time.
19. The apparatus of claim 11 , wherein the frequency synchronization signals are pilot symbols.
20. The apparatus of claim 11 , wherein the transmitter is a base station, and the receiver is a remote station.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 28, 1999
August 12, 2003
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